FAQs

When do we have to finish the combustible dust DHA (Dust Hazards Analysis)?
The new cycle of the 652 document is going to set a firm date when all DHA’s have to be finished for existing systems and those that fall under the current 652. That is September 7, 2020. It may be slightly modified but only by a few months to correspond with the commodity standards (e.g. 654, 664, 484, and 61).

We are purchasing and installing a new dust collection system. Do we have to perform a DHA on that system?
Yes, any new system or major modification to an existing system should have a complete DHA performed, but only on the system and the areas it might affect.

What is the minimum combustible dust testing I need to properly design my new dust collection and dust explosion protection system?
If you are unsure whether your dust is combustible or not, you should have a go/no go test performed. If the dust is shown to be non-combustible, you are done. If the dust is shown to be combustible, there are four additional tests you need to properly design your system: KST, PMAX, M.I.E., and M.E.C.

• The KST test tells you the rate of pressure rise, and is measure in bar meters per second (pressure times the cube root of the volume, divided by time.)
• The PMAX is the maximum explosion pressure. Together, these factors determine the severity of the explosion.
• The Minimum Ignition Energy (M.I.E.) test tells you the amount of energy that is required to ignite an explosion.
• The Minimum Explosive Concentration (M.E.C.) tells you the lowest concentration of this dust that will sustain an explosion. These two tests help you determine the likelihood of an explosion.